Study and application of parallel catalytic hydrogen wave of lincomycin in the presence of persulfate

Abstract

The polarographic currents of lincomycin in the absence and the presence of persulfate are studied by linear potential scan polarography and cyclic voltammetry. The reduction wave of lincomycin in phosphate buffer is a catalytic hydrogen wave, which is the reduction of the proton combined with lincomycin in nature. When S 2O 8 2− is present, the atomic hydrogen as intermediate product from the reduction of the combined proton is oxidized by both S 2O 8 2− and its reduction intermediate, sulfate radical anion SO 4 − , to regenerate the original proton, producing the parallel catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave, a novel method for the determination of lincomycin is proposed. In 0.48 mol l −1 KH 2PO 4–Na 2HPO 4 (pH 7.4)–8.0×10 −3 mol l −1 K 2S 2O 8 supporting electrolyte, the peak potential of the parallel catalytic hydrogen wave is −1.82 V ( vs. SCE). The second-order derivative peak current is rectilinear to the lincomycin concentration in the range of 8.5×10 −8–9.0×10 −5 mol l −1 and the detection limit is 4×10 −8 mol l −1. The parallel catalytic hydrogen wave is three orders in magnitude higher than that of the corresponding catalytic hydrogen wave in analytical sensitivity. The proposed method is applied to the rapid determination of lincomycin hydrochloride in eye drops without previous separation.